1. Field of the Invention
This invention relates generally to methods, systems and apparatus for managing digital communications systems. More specifically, this invention relates to managing operational states, such as line profiles, in a DSL system.
2. Description of Related Art
Digital subscriber line (DSL) technologies provide potentially large bandwidth for digital communication over existing telephone subscriber lines (referred to as loops and/or the copper plant). Telephone subscriber lines can provide this bandwidth despite their original design for only voice-band analog communication. In particular, asymmetric DSL (ADSL) can adjust to the characteristics of the subscriber line by using a discrete multitone (DMT) line code that assigns a number of bits to each tone (or sub-carrier), which can be adjusted to channel conditions as determined during training and initialization of the modems (typically transceivers that function as both transmitters and receivers) at each end of the subscriber line.
In most of the deployed Asymmetric Digital Subscriber Line-1 (ADSL1) Digital Subscriber Line Access Multiplexers (DSLAMs) implementations, a “line profile” specifies parameters such as data rate, power spectral density (PSD), margin, forward error correction (FEC) parameters and a carrier mask (CMASK) for a particular DSL customer/line attached to the DSLAM. A “line profile” (also called a “profile”) is different from a “service type,” which refers to the data rate and latency ranges desired/allowed for a line depending on the payment or choice of the customer. Different customers may have different profiles. An example that lists controllable profile parameters appears in the table below:                Profile name: Profile1        Interleaving delay: Low (Fast channel)        Maximum PSD level for downstream: −46 dBm/Hz        Maximum downstream rate: 6016 kbps        Minimum downstream rate: 192 kbps        Maximum upstream rate: 416 kbps        Minimum upstream rate: 64 kbps        Maximum noise margin: 16 dB        Target noise margin: 6 dB        Minimum noise margin: 0 dB        Carrier mask to be used (in hexadecimal format):                    FFF01FFF0FFFFFFFFFFFFFE0001FFFFF0000000000000000 0000000000000000                        
Operators currently use these profiles in a simple manner to control only an individual line's data rate, and perhaps FEC settings. Therefore, an individual line's profile is often selected manually, often causing the line to remain in that profile unless maintenance personnel manually change the profile during a trouble-ticket response or in response to a customer request for a different DSL service. Even when a line is allowed to move automatically to a few other profiles, strong restrictions have been applied, resulting in only a few profiles being considered as candidates for the move. Moreover, the rules for any profile change can be viewed as fixed or static functions of one or a very small number of line-characterizing parameters. Such simple transitions do not permit diverse service types and fail to assist in overcoming and/or addressing various noise impairments (for example, impulse noise and crosstalk noise), thereby limiting deployed data-rate and/or range capabilities of ADSL and Very high speed Digital Subscriber Line (VDSL).
Systems, methods and techniques that permit implementation of a wide variety of line profiles and transitions between such profiles automatically and with ease in communication systems such as DSL systems would represent a significant advancement in the art. In particular, prioritization and implementation of transition options in the communication system would represent a considerable advancement in the field of DSL service rates and associated ranges.